The United Nations says the security situation is improving in Burma's western Rakhine state, where violence between Buddhists and ethnic Rohingya Muslims has left dozens of people dead and tens of thousands displaced.

The U.N. Office for the Coordination of Humanitarian Affairs says reports of clashes have "substantially decreased" over the past three weeks. But it warns that sectarian tensions remain very high with continued sporadic conflicts in some areas.

Burmese authorities say a total of 87 people have been killed since late May, when riots and retaliatory attacks erupted after three Muslim men were blamed for the rape and murder of a Buddhist woman.

The unrest has highlighted the situation of the Rohingya, who are denied citizenship in Burma and not recognized as an ethnic group. Many Burmese consider the country's 800,000 Rohingya to be illegal immigrants from Bangladesh.

Rights groups such as Human Rights Watch and Amnesty International have also accused Burmese security forces of carrying out a campaign of violence and mass arrests against the Rohingya in the aftermath of the unrest.

Burma's government, which has a long history of violence against ethnic minorities, has denied the accusations, saying its security forces acted with restraint. Rakhine state has been under emergency rule since early June.

The government says over 68,500 people are still displaced as a result of the conflict, huddled in 63 refugee camps in Sittwe, Kyauktaw, and Maungdaw townships. Officials say over 5,300 houses were destroyed in the unrest.